Tubular arms in a composite material are known, used to make articulated or telescopic structures, which are moveable and used to support and guide transport means for materials, such as for example pipes to carry concrete or materials similar to concrete.
An example of such arms is described in the European patent EP-B-1.970.344, in the name of the Applicant, which describes arms in composite material pivoted to each other at the ends to form an articulated and mobile structure for heavy vehicles.
The arms in question generally have a substantially square or generically polygonal, circular or elliptical section, which reduces at least according to a characteristic size passing from one end to the other, and a development in length much greater than that of the other sizes.
Said arms can be provided of stiffening and strengthening elements, of connecting elements for the connection to other arms o to moving means, or again of specific equipment based on the several use of the arms.
From EP-A-2.039.498, also in the name of the Applicant, a method to make such arms in composite material is known, which provides a first step in which a suitable quantity of layers of fiber is deposited inside the volume of suitable female molds; the fiber may already be pre-impregnated or impregnated in a subsequent step. The method also comprises a second step in which the composite material is subjected to a heat process, typically in autoclave, and a final step in which the necessary mechanical finishing works are carried out.
One disadvantage of this known method is that the operations to be carried out cannot be done in a completely automated way. Consequently the productivity remains limited, the differences between one embodiment and another of a same model of arm can be considerable and the labor costs cannot be optimized.
A further disadvantage of the known method is that it is difficult for the operating machines to access some areas of the mold, which further complicates the possibility of making the process automated. Moreover, in the case of arms with hollow section, it may be necessary to provide two female molds to make two parts, symmetrical according to a plane passing through the longitudinal axis of the arm, which must then be joined.
One purpose of the present invention is to improve the productive process of the arms in composite material described above, in order to render the process more suitable for automation and therefore guarantee greater productivity.
Another purpose of the present invention is to make a repeatable and producible product with uniform features and with reduced costs and times.
The Applicant has devised, tested and embodied the present invention to overcome the shortcomings of the state of the art and to obtain these and other purposes and advantages.